This invention relates to a light converting type detector, more particularly, to a detector capable of detecting whether a direct current or alternating current high voltage line or electric machines or apparatus are impressed or i.e. not with a potential, or alive or dead, and if they are alive, capable of detecting the magnitude of the voltage or current.
The type, construction and operation of conventional detectors are different depending upon the rated voltage of the electric transmission and distribution lines or electric machines and apparatus. However, those using neon tubes providing visual indications and acoustic type producing sound pulses are used in most cases for confirming whether an electric circuit, machine or apparatus or installation are alive or dead.
However many people die every year due to electric shocks even when such detectors are used and even when they work under safety regulations, because it is impossible to visually confirm presence of high potential.
As shown in FIG. 1, a conventional neon tube type detector comprises an insulating tube 8 made of ebonite, for example, and an insulating operating rod 9. The insulating tube 8 contains a contact piece 1, a capacitor 2, a neon tube 3 and a resistor 5 which are connected in series. When the contact piece 1 is brought near a live portion, a fraction of the voltage thereof is detected through capacitor 2. Neon tube 3 is provided with a view window 4 made of a plastic lens for ready observation. However, such detector can be used in a relatively narrow voltage range of from 100 to several tens thousand volts because in a strong electric field, the neon tube 3 lights before actually contacting the contact piece 1 to a live element. Moreover, it is difficult to see whether the neon tube 3 lights or not because it is mounted on the long insulating rod.
FIG. 2 shows another type of the prior art detector wherein a clip current transformer type AC current meter mounted on an insulating rod 17 is used to measure the current I flowing through a high voltage conductor 10. This detector is constructed to detect the current I flowing through conductor 10 by detecting the magnetic flux produced by the current I by a current transformer 13 formed by a clip 12. The opening and closing of the clip is performed by a knob 16 located near the lower end of the hollow insulating rod 17 through a rod 15 extending through the insulating rod 17. If this type of the detector is used to measure current I flowing through a high voltage conductor, it is difficult to read ammeter 14 because of the length of the insulating rod. Locating the ammeter 14 at a lower portion is not permissible because of the danger of the high voltage. To obviate such difficulties it has been proposed to convert the measured current into an audible pulse which is transmitted through a pipe to be converted into an electric signal for operating an ammeter at a lower position. However, such construction is complicated and not yet used.